that allows the simulation kernel to control its execution: when a user
process requires a blocking action (such as sending a message), it is
interrupted, and only gets released when the simulated clock reaches
-the point where the blocking operation is done.
+the point where the blocking operation is done. This is explained
+graphically in the [relevant tutorial, available online](http://simgrid.gforge.inria.fr/tutorials/simgrid-simix-101.pdf).
In SimGrid, the containers in which user processes are virtualized are
called contexts. Several context factory are provided, and you can
machine because of portability issues. In any case, the default one
should be the most effcient one (please report bugs if the
auto-detection fails for you). They are approximately sorted here from
-the slowest to the most effient:
+the slowest to the most efficient:
- \b thread: very slow factory using full featured threads (either
pthreads or windows native threads). They are slow but very
